The Principal Investigator, David Walterhouse, M.D., is an Assistant Professor of Pediatrics and a Board Certified Pediatric Hematologist/Oncologist. He has approximately 5 years of molecular biology research experience including 2 years of fellowship training spent cloning and characterizing the sequence and expression patterns of fcgamma receptor transcripts in platelets and white blood cells, and 3 years of experience studying expression patterns of the oncogene Gli during normal embryonic development. His primary research interest is directed at the interface of developmental biology and pediatric oncogenesis. For this application, he proposes to learn tissue culture technology and transgenic animal technology under the supervision of Dr. Philip lannaccone, Director of the Markey Developmental Biology Program, and Director of the Northwestern University Transgenic Animal Facility. Building on his previous experiments describing expression patterns of Gli during normal mouse embryogenesis, these techniques will provide important methods of studying Gli function and regulation. Cotransfection assays in tissue culture will be used to test the hypothesis that this zinc finger containing protein functions as a transcription factor. Critical functional domains and critical concentrations will be identified. Gain of Gli function transgenic mice, overexpressing Gli in multiple tissues during specific developmental periods, will be used to test the hypothesis that over expression of Gli will result in cellular hyperplasia, ultimately resulting in congenital malformations or tumors. This hypothesis is supported by the fact that Gli is amplified in specific human cancers. To understand Gli regulation, genomic clones containing 5' regulatory regions will be analyzed by DNA sequencing. Potential promoter regions will be studied functionally by their ability to drive CAT expression in tissue culture. functionally active regions will be used to identify Gli regulatory proteins using gel shift assays. It is the goal of this work to understand the effects of Gli expression during development and during adult life, and to understand how these effects are mediated so that in the long-term preventative strategies or novel treatment strategies for cancer and/or congenital anomalies caused by Gli expression abnormalities may be developed.